Benefitting from the combined properties of intrinsic ceramic materials and advanced porous configuration, lightweight porous ceramics with porosity ranging from 2.3 to 99% and pore size distribution within 3 nm - 3 mm exhibit low density, large specific surface area, high toughness, strong thermal shock resistance, good thermal insulation capability, excellent high temperature stability, and low dielectric constant, which are barely offered by metal, polymer or even their dense counterpart. This unique set of features endow porous ceramics an indispensable role in the future development of sustainable energy and environmental applications. To be successfully applied in these applications, precise selection of the type of ceramics and creation of their detailed structural features of the pores are the most important stages that require intensive investigations and comprehensive understanding. For a given ceramic, the synthesis process is critical for achieving the desired pore configuration and geometry which eventually determines the final properties of the products, including both the usual mechanical properties and other advanced functionalities. In this review, we will first focus on the fabrication processes that determine the pore structures and geometries. Four mainstream fabrication methods: partial sintering, replica template, sacrificial template, and direct foaming will be discussed, in addition to the additive manufacturing technique which has emerged as a promising process for the direct fabrication of porous ceramics components. Each approach demonstrates its unique suitability for a specific range of materials, porosity, pore size, pore connectivity, and pore distribution. The principles and challenges of each synthesis strategies will be summarised and discussed, the progress that can be made to meet the requirement of advanced applications has been clarified. We then focus on the properties derived from different pore features. The superior damage tolerance and thermal insulation capability of porous ceramics, as compared with their dense counterpart, are presented. Thirdly, the great potentials of these interesting porous ceramics for the energy- and environmental-based applications, including filters, catalyst support, energy storage and conversion components, energy harvesting devices, and insulators are highlighted, in association with the criteria and demands for manufacturing processes. It is envisaged that this review will provide a guidance in the manufacture of advanced porous ceramics with desired pore structures and properties tailored for specific applications. Finally, we will demonstrate how these porous ceramics could contribute to the development of current and future energy and environment technologies.

Porous ceramics: Light in weight but heavy in energy and environment technologies

One step co-sintering process for low-cost fly ash based ceramic microfiltration membrane in oil-in-water emulsion treatment

Given that many people suffer from large-area skin damage, skin regeneration is a matter of high concern. Here, an available method is developed for the formation of large-area robust skins through three stages: fabrication of a biodegradable sealant-loaded nanofiber scaffold (SNS), skin tissue reconstruction, and skin regeneration. First, a microfluidic blow-spinning strategy is proposed to fabricate a large-scale nanofiber scaffold with an area of 140 cm × 40 cm, composed of fibrinogen-loaded polycaprolactone/silk fibroin (PCL/SF) ultrafine core-shell nanofibers with mean diameter of 65 nm. Then, the SNS forms, where the gelling reaction of fibrin sealant occurs in situ between thrombin and fibrinogen on PCL/SF nanofiber surface, to promote the migration and proliferation of fibroblasts, accelerating skin regeneration. Through an in vivo study, it is shown that the SNS can rapidly repair acute tissue damage such as vascular bleeding and hepatic hemorrhage, and also promote angiogenesis, large-area abdominal wall defect repair, and wound tissue regeneration for medical problems in the world. Besides, it avoids the risk of immune rejection and secondary surgery in clinical applications. This strategy offers a facile route to regenerate large-scale robust skin, which shows great potential in abdominal wall defect repair.

Large‐Scale Fabrication of Robust Artificial Skins from a Biodegradable Sealant‐Loaded Nanofiber Scaffold to Skin Tissue via Microfluidic Blow‐Spinning

https://hal-cnrs.archives-ouvertes.fr/hal-02615657/document

Silicon carbide filters and porous membranes: A review of processing, properties, performance and application

Lower-temperature preparation of SiC ceramic membrane using zeolite residue as sintering aid for oil-in-water separation

The gas permeability of SiC porous ceramics (SCPCs) is typically proportional to the open porosity. However, an increase in open porosity can decrease the bending strength due to weak contact between particles. In this study, high-permeability SCPCs were prepared using a combination method of dry press forming and in situ reaction bonding. The resulting materials contained doping mullite fibers as a reinforcing agent and maintained sufficient bending strength. The open porosity, mechanical strength, microstructure, gas permeability and thermal shocking resistance were systematically investigated. The presence of the mullite fibers (4%) led to increases in open porosity and bending strength to 46.8% and 15.7 MPa after sintering at 1450 °C for 4 h. Additionally, gas permeability of 1600 m 3 /m 2 ·h·kPa was attained in ceramic wafer and a high gas permeability coefficient of 1.64 × 10 −11  m 2 was achieved, superior values than most porous ceramic materials were reported. The close thermal expansion coefficient between the mullite fibers and silicon carbide confers good thermal shock resistance. The bending strength of 14.5 MPa was maintained after 60 cold-hot cycles (0–800 °C). The new SCPCs show great promise for use as next generation hot-gas filters.

Wei Wei

Papers

High gas permeability of SiC porous ceramics reinforced by mullite fibers

Preparation of non-oxide SiC membrane for gas purification by spray coating